Continuous-wave ignition system

ABSTRACT

A high-frequency continuous-wave ignition system. It employs a control winding with DC bias, to start and stop an oscillator. The start time and duration of oscillator operation takes place as timed by a breaker-pointless means under control of engine crank-shaft angle.

United States Patent 1 Canup Feb. 19, 1974 I [54] CONTINUOUS-WAVE IGNITION SYSTEM 3,593,696 7/1971 Guido 123/148 E 3,418,989 12/1968 Silverman.... 123/148 E [75] Invent: Robert E Calm!" Rlchmmd 3,454,871 7/1969 Nolting 123/148 E [73] Assignee: Texaco Inc., New York, NY. 2,976,461 3/1961 Dilger et al. 123/148 E [22] Filed: 1971 Primary Examiner-Laurence M. Goodridge [21] AppL 193 909 Assistant ExaminerCort Flint Attorney, Agent, or Firm-Thomas H. Whaley; Carl G. Ries [52] US. Cl 123/148 E Int. [58] Field of Search 123/148 E A high-frequency contmuous-wave ignition system. It [56] References Cited employs a control winding with DC bias, to start and stop an oscillator. The start time and duration of oscil- UNITED STATES PATENTS lator operation takes place as timed by a breakerpointless means under control of engine crank-shaft orsc e 3,554,178 1 1971 Boyer 123/148 E angle 3,472,216 10/1969 Clyborne 123/148 E 4 Claims, 3 Drawing Figures r I I l l I9 I I l I 20 I IGNITION I SWITCH l 1 off -I occ. I operate psturt 27/I l 1/ o STARTI S OLENOID I I PATENTEDFEBIQIHH SHEET 1 nr 3 |||l1 lllll J CONTINUOUS-WAVE IGNITION SYSTEM CROSS REFERENCE TO RELATED APPLICATIONS Subject matter of this application relates to copending U.S. Pat. applications of the same inventor as follows:

Ser. No. 67,450

Filed: Aug. 27, 1970 Title: HIGH FREQUENCY CONTINUOUS-WAVE IGNITION ENERGY FOR AN INTERNAL COM- BUSTION ENGINE (D7l,646), and

Ser. No. 100,642

Filed: Dec. 22, 1970 Title: CONTINUOUS-WAVE HIGH FREQUENCY IGNITION SYSTEM (D7l,898).

BACKGROUND OF THE INVENTION This invention concerns ignition systems for an internal combustion engine in general. More specifically, it relates to an improved ignition system applicable to a high-frequency continuous-wave system. And, even more particularly, it relates to such a system that employs a control winding for starting and stopping the high-frequency continuous-wave energy.

DESCRIPTION OF THE PRIOR ART While various ignition systems have been proposed making use of high-frequency continuous-wave energy such systems have been found unsatisfactory. A major reason has been a lack of reliability. Apparently, a major factor in such unreliability has been the erratic starting time for the oscillator that is employed. The applicant has previously disclosed a high-frequency system that employs a control winding for the oscillator in such a manner as to insure instant starting of the oscillator when iginition energy is called for. Such systems have been disclosed and claimed in the above-noted co-pending applications, and it is an object of this invention to provide an improved system of the same type that is particularly applicable to a breakerpointless arrangement.

SUMMARY OF THE INVENTION Briefly, the invention concerns a high-frequency continuous-wave ignition system for an internal combustion engine. The said system employs a control winding for starting and stopping such high-frequency continuous-wave energy, and it has means for timing said energy relative to said engine. In such system, the invention concerns improved means for controlling current flow through said winding in accordance with a predetermined amount of engine shaft angle rotation. It comprises in combination, breakerpointless means controlled by said engine shaft angle for providing a signal pulse having a duration according to said predetermined amount of rotation for each cylinder of said engine. It also comprises electronic means. for cutting off said current flow during each said signal pulse.

Again briefly, the invention concerns a highfrequency continuous-wave ignition system for an internal combustion engine, the said system having a unitary magnetic-circuit type of oscillator that employs a control winding for starting and stopping said oscillator. The system also has means for timing the on-cycles of said oscillator relative to said engine. In connection with a system as set forth, the invention concerns an improvement that comprises means for controlling DC- current flow through said control winding in accordance with a predetermined amount of engine shaft angle rotation, and electromagnetic means including a coil for providing a signal pulse having a duration according to said predetermined amount of rotation for each cylinder of said engine. It also comprises means for inducing said signal pulse in said coil, which means comprises a magnetic flux path coupled with said coil, and permanent magnet means for generating magnetic flux in said path. The signal-pulse inducing means also comprises a rotor, a stator and a variable air gap therebetween for inducing said signal pulse. The improvement also comprises electronic means for cutting off said DC-current flow during each of said signal pulses, which electronic means comprises a NAND gate having two inputs and an output circuit. The improvement also comprises first circuit means for connecting said coil to one of said inputs including a Zener diode for limiting the amplitude of said signal pulse. In addition, it comprises means for applying a. constant amplitude to the other input of said gate whenever said ignition system is energized, and first transistor means in said output circuit for amplifying the output of said gate, as well as a second transistor means controlled by said first transistor means for controlling said DC-current flow in said control winding.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects and benefits of the invention will be more fully set forth below in connection with the best mode contemplated by the inventor of carrying out the invention, and in connection with which there are illustrations provided in the drawings wherein:

FIG. 1 is a circuit diagram illustrating a system ac cording to the invention;

FIG. 2 is a plan view showing a preferred rotor structure for generating an electromagnetic timing pulse, and

FIG. 3 is a transverse cross-sectional view of the structure shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, it is to be noted that the circuit diagram illustrates a system to be used for providing high-frequency continuous-wave ignition energy to an internal combustion engine. Thus, there is a circuit connection 11 that goes to the common circuit element ofa distributor of an internal combustion engine, as indicated by the caption TO DIS. CAP. This connection 11 leads out from a secondary winding 12 that is on a transformer 15 which provides the high-voltage, spark-creating energy. The transformer 15 has a plurality of primary or input windings 14, as illustrated. These are part of an oscillator circuit 16, which is basically like the circuit disclosed in the above-mentioned co-pending US. Pat. application Ser. No. 100,642. Consequently, no detailed explanation of the oscillator operation is needed, However, it may be pointed out that the oscillator 16 employs two pairs of transistors 19 and 20 instead of a single transistor in each case. It will be understood that this does not change the man ner in which the oscillator operates.

The basic oscillator circuit 16 is not new, per se, but, as employed in this case, it makes use ofa control winding 23 that is magnetically coupled with the oscillator windings 14 on the core of the transformer 15. As was the case in the afore-mentioned co-pending application, this control winding 23 acts to control the starting and stopping of the oscillator 16. This involves the application of DC-current flow through the winding 23, along with a low-impedence path, so that when the DC current is flowing and the low-impedence path is effective, the winding 23 will load down the oscillator sufficiently to stop its oscillation. Then, when it is desired to supply spark energy over the output connection 11, the oscillator 16 will be started by removing the DC- current flow through winding 23. The decaying flux thus created will act in the proper direction to cause instantaneous starting of the oscillator 16. The oscillator will, of course, then supply the desired high-voltage high-frequency spark signal over the circuit including output connection 11.

The ignition system is energized whenever a power source, e.g., a I2-volt battery 26, is connected to supply the DC power to the system. This is accomplished in a conventional manner with the circuit from battery 26 being carried via an ignition switch 27 which connects the positive side of battery 26 to a power input circuit connection 30 whenever the ignition switch is either in its start or operate positions. The circuit connection 30 supplies DC power voltage to the oscillator 16 via a fuse 31 and a resistor 32.

At the same time, the positive voltage from battery 26 is connected via a circuit connection 35 to one side of each of three resistors 36, 37 and 38. This provides the power input for an electronic means 42 that is shown enclosed in a dashed-line rectangle. This means acts as part of a breakerpointless ignition control unit, which unit acts in a similar manner and the electromagnetic-pulse generating part of which is substantially like that illustrated and described in the above-noted co-pending U.S. Pat. application Ser. No. 67,450.

Thus, with reference to FIGS. 2 and 3, the breakerpointless arrangement includes a rotor 46 that is carried by a shaft 47. Rotor 46 is surrounded by a magnetic-material stator 48. It will be appreciated that the shaft 47 is mechanically connected (not shown) to the crank shaft of the engine. Thus, the ignition system is arranged in a conventional manner so that the rotation of the shaft 47 and attached rotor 46 will be directly related to the engine shaft angle at all times. The breakerpointless pulse-generating structure, described above, includes a magnetic flux path with the rotor 46, stator 48 and cylindrical permanent magnet ring 51 (FIG. 3) joining a lower plate 52 of magnetic material. This makes a complete flux path while providing electromagnetic coupling therewith by a coil 54 (FIG. 3 and FIG. 1).

There are a plurality of inwardly directed radial projections 55 on the stator 48. These are equal in number to the number of cylinders of the engine, and they extend so as to leave only a small air gap when a corresponding plurality of outwardly directed radial projections 58 on the rotor 46 are in alignment with the projections 55. It will be clear that when these two sets of projections are not in alignment, the air gap is large,

and the result is a substantial change in the flux density through the magnetic path. Such change, of course, generates a signal voltage in the coil 54.

The arrangement of the electromagnetic rotor elements is, as already indicated, substantially like that of the co-pending U.S. Pat. application Ser. No. 67,450. But, in this case the output signals which are generated are treated in such manner as to clip the amplitude of the leading one of the pair of pulses generated as the projections 58 move into and out of alignment with the sharp-pointed projections 55. This limits the amplitude of the pulses generated so that they remain at the same height regardless of engine speed. Also, because of the clipping of the pulse, there is an output voltage during the full time the rotor projections 58 are in alignment with the stator projections 55. Consequently, as will appear more fully below, the system according to this invention gives simplified results and eliminates the need of a special arrangement to shut down the oscillator as was the case in the co-pending application system.

Referring to the electronic means 42, it is pointed out that there is a NAND gate 61 that has an input connection 62 leading from the other end of the resistor 36 from that which is connected to the common connector 35. There is another input connection 65 that connects to one end of the winding 54, in which control pulses are generated. The other end of the winding 54 is connected to ground as shown by a grounded connector 64. And there is a Zener diode 66 connected across the winding 54 along with a capacitor 67 that is in parallel with the diode 66. Thus, both the diode 66 and the capacitor 67 have one side of each connected to the input connection 65 of the NAND gate 61.

There is an output circuit connection 71 that goes from the NAND gate 61 to the base electrode of a transistor 72. The transistor 72 is coupled with another transistor 73 in a Darlington configuration to amplify and feed the output of the NAND circuit 61 via the circuit connection 71 to the input of a power transistor 76.

The output from the transistor 73 goes via a diode 77 that is connected between a pair of resistors 78 and 79. This network goes to the base-emitter circuit of transistor 76. Transistor 76 is connected with its collectoremitter in series with the oscillator control winding 23 via a circuit connection 82 and a diode 83. Part of the winding 23 (oscillator control) circuit also includes another diode 86 and a capacitor 87. The latter two have one side of each grounded, as shown.

OPERATION Briefly, the operation during a single continuouswave high-frequency sparking interval may be reviewed as follows. With the engine running and between sparking intervals, the oscillator 16 is cut off because of the low-impedence path across the control winding 23 that includes the diode 86 and the power transistor 76. Also, a DC current in the winding 23 will apply a magnetic bias to the core of the transformer 15.

Power transistor 76 will be conducting because the NAND gate 61 has a lack of coincidence at its inputs, i.e., there is a continuous positive voltage applied over connection 62 so long as the ignition switch 27 is on.

When the distributor rotor projections 58 reach alignment with the stator projections 55, a positive voltage signal is generated in the winding 54. It is clipped and applied to the other input of the NAND gate 61 over the connection 65. This coincidence of signals causes the output of the NAND gate to go to zero which cuts off the conduction of the transistor 76. That, in turn, cuts off the DC current in the winding 23 which starts the oscillator 16, while the low-impedence path is also removed.

The sparking interval with the oscillator 16 oscillating continues until the trailing edges of the rotor projections 58 pass out of alignment with the stator projections 55. That causes a negative voltage signal to be generated in the winding 54 which throws the NAND gate 61 on again (positive output voltage). This, in turn, turns the power transistor 76 fully on. Then, the next half cycle of the oscillator 16 that applies a positive voltage to the collector of the transistor 76, will load the oscillator and stop it while, at the same time, DC-current flow is re-established in the winding 23.

it will be observed that the system according to this invention does not need any extra elements in the circuit to stop the oscillator if the distributor should stop while the rotor and stator projections are in alignment, because the lack of any generated signal in winding 54 of the distributor (after the clipped voltage falls to zero) causes an anticoincidence at the NAND gate 61 which then stops the oscillator 16 in the manner just described.

While a particular embodiment of the invention has been described above in considerable detail in accor' dance with the applicable Statutes, this is not to be taken as in any way limiting the invention but merely as being descriptive thereof.

What I claim is:

1. In combination with a high-frequency continuouswave ignition system for an internal combustion engine, said system including a square wave oscillator employing a unitary magnetic circuit and including a control winding for starting and stopping said highfrequency continuous-wave energy, said system also including means for applying a low-impedance path to said control winding concurrently with a DC current therethrough between each spark duration interval, and said system including means for timing said spark duration intervals relative to said engine,

improved means for controlling current flow through said winding in accordance with a predetermined amount of engine shaft angle rotation, comprising in combination electromagnetic means including a coil,

means controlled by said engine shaft angle for inducing a signal pulse in said coil having a duration according to said predetermined amount of rotation,

a NAND gate for controlling said current flow through said winding and having two input circuits and an output circuit,

first circuit means including clipping means for applying said signal pulse to one of said input circuits,

said clipping means limiting the amplitude of said signal pulse,

second circuit means for applying a constant signal to the other of said two input circuits,

transistor means for controlling current flow in said control winding, and

third circuit means for connecting said NAND gate output circuit to said transistor means, all whereby said low impedance path and said DC current flow are concurrently applied between each spark duration interval.

2. The invention according to claim 1, wherein said signal-inducing means comprises a magnetic flux path coupled with said coil,

means for generating magnetix flux in said path, and

means for varying the reluctance of said flux path.

3. The invention according to claim 2, wherein said reluctance-varying means comprises a rotor,

a stator, and

a variable air gap therebetween for generating said signal pulse.

4. in combination with a high'frequency continuouswave ignition system for an internal combustion engine, said system having a unitary-magnetic-circuit type oscillator employing a control winding for starting and stopping said oscillator, and having means for timing the on-cycles of said oscillator relative to said engine,

the improvement comprising means for controlling DC-current flow through said control winding in accordance with a predetermined amount of engine shaft angle rotation,

electromagnetic means including a coil for providing a signal pulse having a duration according to said predetermined amount of rotation for each cylinder of said engine, and

means for inducing said signal pulse in said coil comprising permanent magnet means for generating magnetic flux in said path,

a rotor,

a stator, and

a variable air gap therebetween for inducing said signal pulse, and

electronic means for cutting off said DC-current flow during each of said signal pulses, comprising a NAND gate for controlling said DC cut off interval having two inputs and an output circuit, first circuit means for connecting said coil to one of said inputs including a Zener diode for limiting the amplitude of said signal pulse,

means for applying a constant amplitude signal to the other input of said gate whenever said ignition system is energized,

first transistor means in said output circuit for amplifying the output of said gate, and

second transistor means controlled by said first transistor means for controlling said. DC-current flow in said control winding. 

1. In combination with a high-frequency continuous-wave ignition system for an internal combustion engine, said system including a square wave oscillator employing a unitary magnetic circuit and including a control winding for starting and stopping said highfrequency continuous-wave energy, said system also including means for applying a low-Impedance path to said control winding concurrently with a DC current therethrough between each spark duration interval, and said system including means for timing said spark duration intervals relative to said engine, improved means for controlling current flow through said winding in accordance with a predetermined amount of engine shaft angle rotation, comprising in combination electromagnetic means including a coil, means controlled by said engine shaft angle for inducing a signal pulse in said coil having a duration according to said predetermined amount of rotation, a NAND gate for controlling said current flow through said winding and having two input circuits and an output circuit, first circuit means including clipping means for applying said signal pulse to one of said input circuits, said clipping means limiting the amplitude of said signal pulse, second circuit means for applying a constant signal to the other of said two input circuits, transistor means for controlling current flow in said control winding, and third circuit means for connecting said NAND gate output circuit to said transistor means, all whereby said low impedance path and said DC current flow are concurrently applied between each spark duration interval.
 2. The invention according to claim 1, wherein said signal-inducing means comprises a magnetic flux path coupled with said coil, means for generating magnetix flux in said path, and means for varying the reluctance of said flux path.
 3. The invention according to claim 2, wherein said reluctance-varying means comprises a rotor, a stator, and a variable air gap therebetween for generating said signal pulse.
 4. In combination with a high-frequency continuous-wave ignition system for an internal combustion engine, said system having a unitary-magnetic-circuit type oscillator employing a control winding for starting and stopping said oscillator, and having means for timing the on-cycles of said oscillator relative to said engine, the improvement comprising means for controlling DC-current flow through said control winding in accordance with a predetermined amount of engine shaft angle rotation, electromagnetic means including a coil for providing a signal pulse having a duration according to said predetermined amount of rotation for each cylinder of said engine, and means for inducing said signal pulse in said coil comprising permanent magnet means for generating magnetic flux in said path, a rotor, a stator, and a variable air gap therebetween for inducing said signal pulse, and electronic means for cutting off said DC-current flow during each of said signal pulses, comprising a NAND gate for controlling said DC cut off interval having two inputs and an output circuit, first circuit means for connecting said coil to one of said inputs including a Zener diode for limiting the amplitude of said signal pulse, means for applying a constant amplitude signal to the other input of said gate whenever said ignition system is energized, first transistor means in said output circuit for amplifying the output of said gate, and second transistor means controlled by said first transistor means for controlling said DC-current flow in said control winding. 